1. The Field of Invention
The present invention relates to multiple port temperature responsive values and in particular to values for controlling vacuum actuated devices of an internal combustion engine to reduce the emission of pollutants and other noxious gases from the engine.
2. Description of the Prior Art
Multiple port valves have particular utility for conrolling vacuum to vacuum operated devices of an internal combustion engine as is disclosed to a certain extent in U.S. Pat. No. 3,400,698. In this patent, however, the valve is a three port valve in which a vacuum spark advance is selectively connected to two different sources of vacuum in response to a sensed temperature.
Further investigations show that it is desirable to also control an exhaust gas recirculation valve in response to the same temperature conditions as the vacuum spark advance. Simultaneously controlling the vacuum to both the distributor vacuum spark advance and the exhaust gas recirculation valve in response to a predetermined engine temperature, for example, the water temperature in the engine cooling jacket, provides an effective means for controlling engine emission.